Question

Hey guys is the 'null space' for A, the x matrices that would give AX=0?

Answer 1

typically the "x" are vectors, and all of the (non-zero) x's could be put into a matrix.
but yes, the x vectors represent the null space.

Answer 2

well if A is not singular then x=0 works and A shall ne anything, lets say Null would be identity which wont make a difference =)